The objectives of this proposed research are identification of the genetic components in a significant developmental process, analysis of their relationships in the morphogenetic sequence, and understanding of relationships of form and function. The experimental system is the sexual reproductive apparatus of Neurospora. Within the genus are two species, N. crassa and N. tetrasperma, which have homologous morphogenetic sequences and end products that are nevertheless significantly different. Parallel mutants, isolated in each species, block the developmental process at different points. Comparative studies utilizing both light and electron microscopy and made on the normal and different mutant material in both species are expected to give insight into problems such as the formation of new cells from nuclei existing in a common cytoplasm. Another focus of analysis will be on the properties of a phase specific protein, present as electrophoretic variants in different neurosporas, that is undetectable, if at all present, in asexual material but appears shortly prior to mating and increases dramatically after fertilization. Localization of the protein will be sought by the combined use of conjugated antibody and microscopy. Attempts to define the function of the protein will follow. Broader understanding of the experimental system is expected to emerge from transfer of relevant genetic material from one species to another. The meaning of dominance relationships between mutant genes and their wild-type alleles will be explored.